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(No Model.)

0. F. G. M. B. DE LA TOUANNEQ TELEPHONE EXCHANGE APPARATUS.

No. 535,745. Patented Mar; 12', 1895-.-v

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UNITED STATES PAT NT OFFICE.

CHARLES FELIX GASTON MARIE BIGOT DE LA TOUANNE, OE PARIS, FRANCE.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 535,745, dated March 12, 1 895.

Application filed December 30, 1893. Serial No. 495,198. (No model-) To aZZ whom it may concern:

Be it known that 1, CHARLES FELIX GAs- TON MARIE Broom DE LA TOUANNE, a citizen of France, residing at Paris, France, have inventeda certain new and useful Improvement in Telephone-Exchange Apparatus, (Case No. 1,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone exchange apparatus, audits object is to reduce the number of contacts at the switch board for each telephone line, and at the same time to facilitate making the calls between the subscribers stations and the central office, and the con-- nection and disconnection of the lines.

My invention consists, first, in a telephone system in which each subscriber is provided with a pair of keys, whereby when one key is depressed one limb of the line is connected with said subscribers generator, or source of I ,ringing currents, and when both keys are deerator when the first key is depressed, whereby buta single key need be depressed in sending a elearing-out signal.

My invention consists, second, in a telephone system comprising two limbs, a "ground connection through an annunciator from each of said limbs, a source of electricity having one pole grounded, means for connecting said source of electricity with one of said limbs, whereby the annunciator in the ground connection therefrom will be operated, means being also provided for grounding the end of the other ofsaid limbs, whereby the current which does not pass to ground through said first annunciator will be shunted past the annunciator connected with said second limb so as not to operate the same.

My invention consists, third, in a line switch in which the line spring, as heretofore constructed, is replaced by a rigid contact piece, the plug being provided with a yieldingly mounted tip, whereby, when said plug is inserted in the switch, contact will be maintained between the contact piece and the plug tip by the resiliency of thelatter.

Each subscribers line is connected at the central oifice according to the parenthesis system, with a switch'upon each of the sections of the switch board, said switches preferably comprising a ring connected with one limb of the telephone line, which ring may also serve as the test ring, and a rigid contact piece connected with the second limb of the telephone line. Upon some one of the sections of the switch board each subscriber is provided with an individual or answering spring jack switch and an individual annunciator. This answering switch comprises a ring connected with one limb of the telephone line and a line spring connected with the second limb, the line spring normally resting against its contact anvil which is connected to ground through the individual annunciator.

The operators apparatus comprises a pair of plugs, one of which is of ordinary construction comprising a metallic tip and a metallic sleeve adapted to make contact when inserted in the subscribers answering switch with the line spring and the test ring respectively. The other plug is of novel construction and is adapted to be inserted into the line switches, which, as before stated, are provided with rigid contact pieces, and, in order to effect an electrical contact between the tip of said plug and said rigid contact piece, the former is adapted to be flexed transversely and is made resilient so that a-firm pressure between the tip of the plug and the contact piece may be maintained. The sleeves of the plugs are united by a strand as are also the tips. In aground connection from the sleeve strand is included the clearing out annunciator, which, when connection is made with any line willthus be in electrical connection with the limb of the telephone line opposite to that to which the individual annunciator is normally connected. The operator is provided with a telephone set which is adapted to be bridged between the sleeve and tip strands of the plug connection by means of a bridging in key. Keys are provided in the sleeve strand through the agency of which either section of the sleeve strand may be independently connected with the generator of ringing currents, which is included in a ground connection.

Each subscriber is provided with a key which normally rests in position to include the subscribers bell in circuit, and which, when depressed, disconnects the bell from the circuit and connects one limb of the telephone line with the generator. Each subscriber is also provided with a second key which, when depressed, serves to connect the second limb of the telephone line with the generator. The individual annunciator being connected with the second limb it is necessary in sending a calling current to depress both keys. When the subscribers are in communication the clearing out annunciator is included in a ground connection from the first limb so that to send in a clearing out signal it is necessary to depress but the first key.

By the above arrangement it will be observed that all ringing currents are provided with a ground return, while the talking circuit is completely metallic. It is to be further noted that. calling currents are sent over one limb of the telephone line while clearing out currents are sent over the other limb. By this system the individual annunciator of the called subscriber is included in a ground connection from the talking circuit, and it will be observed that, if the calling subscriber should send in the clearing out signal before the called subscriber should hang up his telephone, a portion of the clearing out current would be shunted past the clearing out annunciator and pass to ground through the individualannunciatorof the called subscriber, thus giving a false signal. To prevent such an occurrence, I provide means at the subscribers station for closing to ground the limb which is not connected with the generator, thus furnishing a path of low resistance to ground, which shunts the clearing out current past the individual annunciator of the called subscriber.

My invention may be used in connection with any suitable test system.

The test system that I have particularly illustrated is that described in Letters Patent No. 442,143, granted to Charles E. Scribner December 9, 1890.

My invention will be more readily understood by reference to the accompanying drawings, in which Figure 1 is a diagrammatic illustration of my invention. Fig. 2 is a detail view of the connecting plug provided with a resilient tip.

Like letters refer to like parts in both figures.

Referring to Fig. 1, the subscribers station A is connected with the central office by means of the limbs a, a, the limb a being connected with the ring of a spring jack upon each section of the switch board at the central office, twosections only of the switch board being illustrated. Thus, the ring bof the springjack b is connected with the limb a, as is also the ring 0 of the spring jack 0, the spring jack 1) being placed upon the section d of the switch board while the spring jackc is placed upon the section d. The other limb a of the telephoneline is connected with the contact piece b ot spring jack 1) and with contact piece 0 of switch 0. Likewise subscriber B is connected with the central office by limbs e e, the limb e being connected with ringf of switchfupon section (1 of the switch board, and with ring 9' of switch g upon section d. The limb e is connected with contact piece f of switch f, and with contact piece of switch g.

Each subscriber is provided at the central office with an individual annunciator and an individual answering jack which are placed upon some one section of the switch board, each subscriber being thus provided with a spring jack upon each section of the multiple switch board, and, in addition, an answering jack and an individual annunciator placed upon some one of said sections.

In Fig. 1 the answering jack h and individual annunciator k of subscriber A are represented as upon the section d of the board, while the answering jack 1' and individual annunciator i of subscriber B are represented as being upon section d. The answeringjack comprises a ring it connected with the limb or of the telephone line, a line spring 72. connected with the limb a and normally resting upon its contact anvil 7L3 which is connected to ground through theindividualannnnciator h. The answeringjack 2' of other subscribers lines are similarly constructed and similarly connected with their individualannunciators.

At the subscribers station the telephone book normally rests against contact 70' which is in electrical connection with a key 70 adapted to make contact either with contact point 70 or contact point 70 said key normally resting against contact 70 which is connected to ground through a bell 7c. The contact point it is connected to ground through a source of calling currents 70 which may be either a battery or generator, the key 70 being provided with ahandle by means of which it may be depressed to make-connection with the battery to send a calling current over the line.

Movable with the key k but insulated therefrom is asecond key k, which, when depressed by the act of depressing key 70 makes contact with contact point 713 connected by conductor a with the limb a of the telephone line. Key k is in electrical connection with a key Yo which normally rests against a contact point 70 connected with ground and when depressed is adapted to make connection with a back contact 10 which is in electrical connection with the contact point of the telephone switch.

Subscriber B is likewise provided with a telephone hook 1, moving between contact points Z and Z and with a key Z moving between contact points l and Z to close circuit through the bell Z 01 the battery 1".

The operators apparatus comprises a pair of plugs m and it having their tips connected by a tip strand 0 and their sleeves connected by a sleeve strand 0'. In the sleeve strand is included a pair of keys 0 0 normally resting against contact points 0 0 to maintain the two sections of-the sleeve strand in electrical connection. Back contact points 0 o are connected with one pole of a battery or generator 0 the other pole of which is grounded, whereby either section of the sleeve strand may be connected with the battery 0 to send a calling current over the line. Between the sleeve strand o and ground is placed the clearing out annunciator p, and in this ground connection is included a battery 0 adjusted as to potential so that it will prevent a passage of the talking currents to ground through the clearing out annunciator. Between the sleeve strand 0 and the tip strand 0 is bridged the operators telephone set, a bridging-in key being provided, whereby the connection may be made or broken. This key comprises a plunger 1) and springs 13 19 adapted to make contact with contact points 19 19 when the plunger is depressed, and to break contact therewith when the plunger is raised. The transmitterp and receiver p are included in circuit between said springs and the receiver is provided with a half connection 19 to ground, the purpose of which will beheieinafter described. Between the receiver and the springp is placed a condenserqa, the function of which will be described hereinafter.

One of the plugs of each set is provided with a flexible tip n, best shown in Fig. 2, which may be formed from a numberofwires bunched together, or in any preferred manner, the idea being to render the tip resilient,

.whereby it may be flexed transversely. In

this connection I do not desire to limit myself to the precise construction of resilient tip illustrated, but desire to claim this feature broadly. Eat-h plug is also provided with a sleeve, as usual, adapted, when inserted in the switch, to make contact with the ring.

All of the switches, with the exception of the answering jack, are provided with fixed contact pieces instead of the flexible springs as heretofore used, the electrical connection between the tip of the plug and the contact piece being maintained by the resiliency of the tip.

Iwill now describe the operation of th system. Suppose the subscriber at station A desires to talk with the subscriber at station B. The first operation is to depress keys 70 and 70 thus completing circuit from ground through battery k key it key is, key 10 limb a, spring contact 72 of the answering jack, contact 71 individual an'nunciator h to ground. The operatorat section 01 seeing the drop fall inserts the plug of her set which is provided with the fixed tip, and which may be called the answering plug, in the answering jack of subscriber A, which jack, as before stated, is supposed to be located upon section (1. By the insertion of the plug, line spring 712 makes contact with the tip of the plug, being thereby raised from its contact anvil 77. to out the individual annunciator h out of circuit. The sleeve of the plug makes contact with the ring it. Thus the sleeve strand of the operators plug connectors is connected with the limb a of the telephone line and the tip strand with the limb a. The operator then depresses her bridging-in key 19, thus throwing her telephone set in circuit between the tip and sleeve strands of the plug connectors. Having received the order from subscriber A to connect with subscriber B, she proceeds to test the line of subscriber B to determine whether or not said line is in use. If the line of subscriber B is in use the rings f, g, &c., of the several spring jacks connected with said line will be electrified to a potential above that of the earth, since the battery 0 of the operators apparatus with which the line may at the time be connected, will be electrically connected with said rings through the sleeve strand of said operators apparatus. It is evident, therefore, that if the operator at section 01', who has. received the order for the connection, makes connection from ring g of the spring jack at her board to ground through a telephone and hears a click, it will be notice to her that the line is busy, and if she hear no click, that the line is free. Such a connection is obtained by touching the tip a of the operators plug to the ring g, her bridging-in key p being already depressed, circuit being thus closed from ring g to tip it and the tip strand 0, spring 19 operators telephone set to ground by half connection 19 In order to prevent the battery 0 from sending current through the telephone set when the bridging-in key is depressed, the condenser 19 is placed between said battery and said telephone set.

Suppose that the operator finds that the line is free. She then inserts plug it into switch g and depresses key 0 thus sending current from battery 0 to key 0 sleeve strand 0', sleeve of plug 01, ring g, limb e, telephone hook Z, which is depressed, the telephone being hung thereon, key Z and bell Z to ground, thus apprising subscriber B that he is wanted at the telephone. Subscriber B having an= swered, the operator raises her bridging-in key p and the subscribers are in connection, the circuit being as follows: from the telephone set of subscriber A over limb a to spring contact 7L2, tip of the plug 172, tip strand 0, tip of plug 71., contact piece g limb e, telephone set of subscriber B, contact Z telephone hook Z, limb e, ring 9, sleeve of plug n, sleeve strand 0', sleeve of plug m, ring it, limb a, telephone hook 70, contact k back to telephone set of subscriber A. The subscribers having completed their conversation hang up their telephones and depress their clearing out keys, Suppose both hang up their telephones and A depresses key k circuit is then closed from ground through battery to key 70 telephone hook 7c, limb a, sleeve strand 0, clearing out annunciator p to ground, the potential of battery 70 being sufficient to overcome battery 0". A portion of the current also passes from sleeve strand 0' to limb e, telephone hook Z, key Z through bell Z to ground. The operator seeing the drop of the clearing out annunciator fall, disconnects the lines. If, instead of A sending in the clearing out signal, B had depressed key Z circuit would be closed in a similar manner through clearing out annunciator 19.

It will be observed that in the operation as above described, both subscribers hung up their telephones before A sent in the clearing out signal. If, however, A sends in the clearing out signal before B hangs up his telephone, the portion of the clearing out current that is shunted past clearing out annunciator 19, and ordinarily actuates the bell of subscriber B, would pass to limb e of the line of subscriber B, and has a tendency to pass to ground through the individual annunciator 2' of said subscriber, thus throwing down the drop and giving a false signal. By the arrangement of the simultaneously acting keys k and 7c", however, this false signal is prevented, for, by the depression of key 10 to send in the clearing out signal, key 70 is simultaneously depressed to ground the end of limb a of the line of subscriberA, which is in electrical connection with the tip strand 0 and limb e of the line of subscriber B. A shunt circuit is thus provided around the individual annunciator of the called subscriber, and the current passing through said annunciator is rendered insufficient to throw down the drop.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The combination with a telephone line comprising two limbs, of a source of calling currents, a key adapted to be depressed to connect said source of currents with one limb of said telephone line, and a second key adapted, when depressed in addition to said first key, to connect said source of currents with said second limb; whereby when one of said keys is depressed one of said limbs is connected with said source of calling currents, and when bothkeys are depressed both of said limbs are so connected, substantially as described.

2. The combination with a telephone line comprising two limbs, of an individual annunciator normally in a ground connection from one of said limbs and adapted to be disconnected therefrom when connection is made with said subscribers line as a calling subscriber, a grounded source of electricity at the subscribers station, a pair of keys adapted, when depressed, to connect said source of electricity with the limb connected with said individual annunciator, whereby a calling current may be sent through said individual annunciator, a grounded clearing out annunciator adapted to be connected with said second limb by theact of connecting with the line, said second limb being alone connected with the source of electricity when one of said keys is depressed; whereby a clearing out current may be sent through said clearing out annunciator, substantially as described.

3. The combination with the two limbs of a telephone line in electrical connection at one end, of a connection to ground from each of said limbs containing an annunciator, a grounded source of electricity, a switch for connecting the end of one of said limbs with said source of electricity, whereby the annunciator connected with said limb may be operated, and means for simultaneously grounding the end of the other of said limbs, whereby the portion of the current not passing to ground through said first annunciator will be shunted past said second annunciator, and said second annunciator be unaffected, substantially as described.

4. The combination with a metallic circuit extending between two subscribers telephones, of a clearing out annunciator in a ground connection from one of the limbs of said circuit, an individual annunciator in a ground connection from the other of said limbs, a grounded source of electricity at the subscribers station, a switch adapted to connect with said source of electricity the end of the limb to which said clearing out annunciator is connected, whereby a clearing out signal may be transmitted, and a simultaneously actuated switch adapted to connect the end of the other limb to ground, whereby such portion of the current as does not pass by the clearing out annunciator to ground will be shunted past the individual annunciator and the latter prevented from giving a false signal, substantially as described.

5. The combination with a switch socket provided with a rigid contact, of a plug provided with a resilient tip adapted when the plug is inserted in the socket to be bent aside and form a rubbing contact with said rigid contact, substantially as described.

In witness whereof I hereunto subscribe my name this 30th day of June, A. D. 1893. CHARLES FELIX GASTON MARIE BIGOT DE LA 'l'OUANNE.

Witnesses:

W. CLYDE J ONES, GEORGE L. CRAGG. 

